Global cessation of bivalent oral polio vaccine (bOPV): A comprehensive review of modeling studies from 2000 to 2025.

BACKGROUND: Oral polio vaccine (OPV) has been central to the Global Polio Eradication Initiative (GPEI)'s efforts due to its ability to interrupt transmission. Yet, because OPV contains live-attenuated virus, its continued use carries risks, especially the emergence of circulating vaccine-derived poliovirus (cVDPV) in under-vaccinated communities. To reduce these risks, phased OPV cessation by serotype began in 2016 with the global "switch" from trivalent OPV (containing types 1, 2, and 3) to bivalent OPV (bOPV, containing types 1 and 3) after the eradication of wild poliovirus type 2. However, continued post-switch cVDPV type 2 outbreaks demonstrated the complexities of safe OPV cessation. Along with persistent wild poliovirus type 1 transmission and cVDPV outbreaks of other serotypes, these experiences underscored the need for evidence-based strategies to guide bOPV cessation.

AREAS COVERED: We conducted a comprehensive review of modeling studies published from 2000 to 2025 that inform OPV cessation planning. 116 articles met our inclusion criteria. These studies examined OPV cessation's prerequisites, follow-up actions, and response strategies. We compared model types and assumptions. We synthesized modeling insights across decision-relevant themes: pre-cessation planning of routine immunization (RI) and supplementary immunization activities (SIAs), post-cessation risk management, surveillance, and vaccine stockpiling.

CONCLUSIONS: The included articles emphasized: (i) implement multiple, high-quality bOPV SIAs over several years until cessation, with coverage levels and target age groups tailored to countries; (ii) strengthen RI before cessation by increasing coverage and introducing a immunologically effective IPV schedule of at least two doses; (iii) maintain high RI IPV coverage, rapid and high-quality outbreak response using available homotypic OPV, and strict containment protocols after cessation; (iv) ensure sensitive surveillance and adequate vaccine stockpiles before, during, and after cessation. These findings informed the Strategic Advisory Group of Experts on Immunization in its endorsement of GPEI's bOPV cessation policy framework. Nonetheless, important gaps remain, including how to measure population immunity and define target thresholds for cessation readiness considering subnational heterogeneity, whether globally synchronized cessation is necessary or geographically phased approaches could achieve comparable risk reduction, and how the availability of novel OPV formulations may influence cessation strategies. Future studies should incorporate subnational data, reflect new vaccine characteristics, and integrate diverse modeling approaches to guide more context-specific decisions.